Romney’s stunning change of heart, after two years of strenuously denying he had any interest in seeking the Republican nomination again, appears to have evolved in just the last few weeks. And, just as quickly, he has been developing a rationale for a third bid, say supporters he spoke with recently.

Economic stewardship would still lie at the core of a Romney campaign, as it did in 2012, but he also would seek to turn some past weaknesses into strengths. The candidate — once lampooned for his wealth and caught on video dismissing the 47 percent of voters on government assistance — has been telling supporters he would run on an antipoverty platform. And while a trip abroad proved to be a low point of his 2012 campaign, he is making the case that he is uniquely qualified on foreign affairs.

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Underlying it all is the notion that, in the mind of Romney and his top advisers, the country made a mistake in not electing Romney in 2012. They want to give the country another shot at sending him to the White House.

“If you believe in your heart that this country is going to hell in a hand basket and is worse than ever, you owe it to your country to think about this,” one longtime Romney adviser said. “There’s a burden there to think this thing through carefully.”

“But there needs to be a rationale,” the adviser continued. “If we made one mistake — and we made more than one in ’12 — it was in not making people understand this is the Turnaround guy.”

Romney’s escalating moves toward a run have created a dizzying atmosphere for his tight-knit circle, filled with conference calls and meetings. While he is facing some skepticism, a tougher road to the nomination, and a fair amount of head-scratching — even among his former network of campaign aides and donors — it is starting to look increasingly likely he will mount a third campaign.

“I would be surprised at this point if he didn’t get in,” a person close to Romney said.

Romney is planning to speak on the USS Midway aircraft carrier Friday night as part of the Republican National Committee’s winter meetings in San Diego, intensifying his push among party officials after announcing to top financial contributors privately last week that he is thinking about getting in the race.

“Maybe he’s been pushed by people around him for months to run,” one donor who was in the room last week said. “But this feels like a guy who only came to grips with it over a two- or three-week holiday. I really think this was a December decision.”

In the months after he lost the 2012 general election campaign to President Obama, Romney’s advisers began encouraging him to consider another run. Romney batted down the ideas with self-deprecating humor. But behind the scenes, he also continued doing something unusual for a man in self-proclaimed political retirement: He carefully tended to his former network of big campaign contributors.

He called them to check in, met with them whenever he traveled, and shared meals with them.

In recent months, Romney began to express more openness to the idea of another shot.

“Circumstances change. Just ask Barack Obama,” said longtime Romney adviser Eric Fehrnstrom, who has handled communications for Romney’s two previous presidential campaigns and worked for him in the Massachusetts State House. “In Mitt’s case, he’s received an incredible amount of encouragement from people he respects and admires, and as a result, he’s giving the race a second look.

“At home, our economy is still not as strong as it could be, long-term growth is in doubt, wages are stagnant, and around the world there’s deep concern that as America’s leadership has unraveled, hostile forces have filled the vacuum,” he added. “Mitt Romney was right on these issues in the last campaign, and I expect if he runs again they will form the core of another campaign for president.”

Over the holidays, Romney gathered with his family in the ski resort of Park City, Utah. In between Christmas services with the Mormon Tabernacle Choir, a Brigham Young basketball game, hanging 22 stockings over a very large fireplace — as well as a chance encounter with Conan O’Brien — the family discussed whether its patriarch should again run for president.

Ann Romney, once cool to the idea, shifted over the past few months and is now encouraging her husband to run again, a person close to the family said. Romney’s oldest son, Tagg, has also been encouraging Romney to run for several months. Romney’s other sons have mixed views, but all have said they would be supportive if he decides to get in the race, the person close to the family said.

Spencer Zwick, who has been Romney’s financial director, also has been a driving force. Zwick met with several other candidates over the past year, but he has remained loyal to Romney and has kept in near-daily contact with donors.

“I believe Mitt Romney is too much of a patriot to sit on the sidelines,” Zwick said. “He knows how to do this.”

In December, some of Romney’s former donors began letting him know that former Florida governor Jeb Bush, a likely candidate, was soliciting them. They suggested that, if he had any designs on running again, he needed to take some action to stem any defections.

Early last week, Zwick began making phone calls to donors in New York. Romney was going to be in town doing business with Solamere Capital, the firm that Zwick runs with Romney’s oldest son, Tagg, and where Romney serves as an adviser.

While in town Friday, Zwick told the financial contributors, Romney wanted to meet in the offices of Woody Johnson, the owner of the New York Jets and a former Romney financial supporter.

Inside a glassed-in conference room, about 25 donors sat around a table. Several more listened in on a speaker phone. Hedge fund titan and billionaire Julian Robertson dialed in from New Zealand.

Those in the room told Romney that he needed to outline a clear rationale for getting into the race, and Romney outlined the three issues that were driving him: poverty, foreign affairs, and long-term economic stability.

But nearly an hour of the 90-minute session was devoted to Romney’s past campaign, and what he needs to fix if he runs another. Several were adamant: He had to clean house, and couldn’t rely on the same team as he did last time. Romney agreed, telling the room that he had been led down the wrong path on some things, and his campaign failed to fully articulate his rationale for running.

They urged Romney to be more comfortable in public, to come across like he did in the documentary “MITT,” released last year. Some close to Romney say they’ve seen a looser side to him lately, citing him putting bunny ears over former Massachusetts Senator Scott Brown during Governor Charlie Baker’s inauguration.

One of Romney’s core arguments for running in 2012 — as a business executive who could step in as Economic Mr. Fix It — would be harder to make with a vastly improved economy. Romney, in his recent private conversations, has asserted he can make long-term structural changes in the economy to help the middle class.

He also has talked about the 50-year war on poverty, launched by President Lyndon B. Johnson in 1964, and about foreign crises, seeking to portray himself as uniquely qualified to address them.

If Romney were president, one longtime adviser said, “There wouldn’t be an ISIS at all, and Putin would know his place in life. Domestically, things would be in better shape.”

Romney was criticized during the 2012 campaign for calling Russia the chief geopolitical foe. His supporters felt vindicated a year later when Russian President Vladimir Putin became a global menace. Pointing to polls that have indicated the former Massachusetts governor could now win a head-to-head matchup with President Obama, Romney seems to believe he could convince voters he was right all along.

But Romney’s Republican rivals — not to mention Democrats in a general election — would have plenty of ammunition against a self-proclaimed antipoverty candidate who once said in 2012, “I’m not concerned about the very poor.”

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